1. Field of the Invention
The present invention relates to a pallet changer apparatus for exchanging pallets between a setup position on a table, at which setup for the processing of a workpiece is performed, and a processing position on the table at which the workpiece is processed.
2. Description of the Related Art
A machining center described in, for example, Japanese Examined Patent Publication No. HEI 7-41503, has a structure in which pallets are interchanged between a setup position and a processing position by operating a pallet changing arm in a turning manner. In this structure, the pallets are removed from each of the two positions by raising the pallet changing arm before turning it, and the pallets are placed at each of the two positions by lowering the pallet changing arm after turning it.
In the above-described structure, the pallet changing arm is raised, lowered and turned by a motor and a cylinder disposed below the table. Therefore, the entire size of the table is large so that the table impedes an operator from performing operations smoothly. Also, because the motor is disposed below the table, it is difficult to access to perform maintenance on the motor. Furthermore, since the drive times of the cylinder and the motor needs to be determined based on output signals of sensors, there exists a rather high possibility of a malfunction, thereby resulting in decreased reliability.
Accordingly, it is an object of the present invention to provide a pallet changer apparatus that achieves high reliability and allows an operator to easily perform required operations.
In accordance with the invention, a pallet changer apparatus for changing pallets between a setup position on a table, at which a setup for a processing is performed, and a processing position on the table, at which a workpiece is processed, includes a pallet changing arm that holds the pallets, a turning mechanism that turns the pallet changing arm between the setup position and the processing position, a raising/lowering mechanism that removes the pallets from the setup position and the processing position by raising the pallet changing arm, and that places the pallets at the setup position and the processing position by lowering the pallet changing arm after turning the pallet changing arm, and a drive force source that generates a drive force for the raising/lowering mechanism and the turning mechanism. The drive force source is provided above the table.
In the above-described pallet changer apparatus, the pallet changing arm is moved up and down and turned by using the single drive force source provided above the table. Due to this structure, the table can be reduced in size so as to allow an operator to perform operations without being impeded by the table. The structure also eliminates the need to determine the drive times of a plurality of drive sources based on output signals of sensors, thereby decreasing the possibility of a malfunction and improving reliability. Also, because the motor is disposed above the table, it is convenient to access to perform maintenance on the motor.
The pallet changer apparatus may further include a first cam drive portion that transmits the drive force from the drive force source to the turning mechanism at a set timing, and a second cam drive portion that transmits the drive force from the drive force source to the raising/lowering mechanism at a set timing.
Since the drive time of the turning mechanism and the drive time of the raising/lowering mechanism are set by the first cam drive portion and the second can drive portion, the pallet changing arm is turned and raised and lowered reliably at the set timings without malfunctioning. Therefore, the reliability of the apparatus further improves.
The pallet changer apparatus may further include a partition cover provided between the setup position and the processing position. The partition cover is connected to the turning mechanism and the raising/lowering mechanism.
The provision of the partition cover prevents an undesired event such as, for example, during the processing of a workpiece, processing debris traveling from the processing position to the setup position. Furthermore, since it is unnecessary to provide dedicated drive force sources to turn and raise and lower the partition cover, the apparatus structure can be simplified.